Let’s Dive into CMMG, Inc MK3 Action Spring, Carbine
The CMMG, Inc MK3 Action Spring, Carbine is a seemingly small, yet crucial component in the AR-15 platform, specifically designed for the CMMG Mk3 rifles. As an experienced armorer and avid shooter, I understand the critical role a properly functioning action spring plays in ensuring cycling reliability and consistent performance. This review will delve into the specifics of this spring, exploring its strengths, weaknesses, and overall value.
My journey to seeking this spring began with a persistent cycling issue in my dedicated .308 AR pistol build. I was experiencing frequent failures to eject, despite trying various buffer weights and gas adjustments. This led me to suspect a weakening or out-of-spec action spring could be the culprit.
Upon receiving the CMMG, Inc MK3 Action Spring, Carbine, I was initially struck by its unassuming appearance. It looked like any other AR-15 carbine spring, but a closer examination revealed tighter winding and what felt like a slightly higher spring rate than some of the generic springs I had on hand. The material appeared to be of good quality, exhibiting a uniform finish and no visible imperfections.
Compared to a standard mil-spec carbine spring, the CMMG spring felt noticeably stiffer, suggesting a potentially higher level of force applied during cycling. I had also considered a Sprinco Red or Blue spring but opted for the CMMG due to its specific design for the Mk3 platform and its budget-friendly price point. I was hoping for improved reliability without introducing excessive force that could cause other issues.
My first impression was one of cautious optimism. The spring seemed well-made, and the increased tension hinted at the potential for improved cycling. However, I reserved judgment until I could put it through its paces at the range.
Real-World Testing: Putting CMMG, Inc MK3 Action Spring, Carbine to the Test
First Use Experience
My first test of the CMMG, Inc MK3 Action Spring, Carbine took place at an outdoor shooting range, under relatively mild conditions (70 degrees Fahrenheit, clear skies). I installed the spring in my .308 AR pistol, paired with a standard carbine buffer and adjustable gas block. I ran a variety of ammunition through it, including both factory loads and my own reloads.
The immediate difference was noticeable. The rifle cycled with a more authoritative feel, and the ejection pattern became significantly more consistent. Previously, spent casings were ejecting erratically, sometimes weakly dribbling out of the ejection port. With the CMMG spring installed, they were ejected with more force and landed in a tighter group.
Initially, I didn’t encounter any issues. The rifle ran smoothly through several magazines. I did notice that the bolt velocity seemed slightly higher, which is to be expected with a stiffer spring. No adjustments to the gas block were immediately necessary.
Extended Use & Reliability
After several range sessions and approximately 500 rounds through my .308 AR pistol, the CMMG, Inc MK3 Action Spring, Carbine has proven to be a reliable upgrade. It has consistently cycled a wide range of ammunition without any failures to eject or feed. The rifle has remained reliable even after being exposed to dusty conditions, confirming the spring’s ability to function under less-than-ideal circumstances.
So far, I have observed no noticeable signs of wear and tear on the spring. It retains its original length and tension, indicating good material quality and construction. Maintenance has been simple: I simply wipe it down with a lightly oiled cloth during routine rifle cleaning.
Compared to my previous experience with generic carbine springs, the CMMG spring has definitely outperformed. It offers a noticeable improvement in cycling reliability and consistency, which is particularly important for a firearm chambered in a larger caliber like .308. I can now confidently run my AR pistol without the constant worry of malfunctions.
Breaking Down the Features of CMMG, Inc MK3 Action Spring, Carbine
Specifications
The CMMG, Inc MK3 Action Spring, Carbine is designed specifically for use in CMMG Mk3 rifles and AR-10 platforms that utilize a carbine-length buffer tube. It is a steel spring, wound to provide a specific spring rate intended to optimize cycling for these larger caliber AR variants. According to CMMG, it’s optimized for their .308 rifles, but can function well in other similar builds.
The specifications matter because the action spring is a critical component in the AR-15’s operating system. It provides the force necessary to return the bolt carrier group forward after each shot, chambering a new round and ensuring the rifle is ready for the next shot. A spring that is too weak can cause failures to feed or eject, while a spring that is too strong can cause short stroking or other malfunctions. This spring being designed specifically for the MK3 system can help reduce those errors.
Performance & Functionality
The CMMG, Inc MK3 Action Spring, Carbine excels at providing reliable and consistent cycling in AR-10 and CMMG Mk3 platforms. It provides sufficient force to chamber rounds and eject spent casings reliably, even with a wide range of ammunition types. The primary strength is its enhanced reliability compared to weaker, generic carbine springs.
The only potential weakness is that the increased spring rate may be too aggressive for some builds. If a rifle is already over-gassed or has a lightweight bolt carrier group, the CMMG spring could potentially exacerbate cycling issues. However, in my experience, this is easily addressed with an adjustable gas block or heavier buffer.
Overall, the CMMG, Inc MK3 Action Spring, Carbine meets and even exceeds expectations for its intended purpose. It’s a simple but effective upgrade that can significantly improve the reliability of an AR-10 or CMMG Mk3 rifle.
Design & Ergonomics
The design of the CMMG, Inc MK3 Action Spring, Carbine is straightforward: a coil spring made of high-quality steel. It is similar in appearance to a standard AR-15 carbine spring, but with a slightly higher spring rate. The build quality is excellent, with a uniform finish and no visible imperfections.
Installation is simple and requires no special tools. The spring simply replaces the existing action spring in the buffer tube. There is no learning curve involved, making it an easy upgrade for even novice gun owners.
Durability & Maintenance
Based on my experience so far, the CMMG, Inc MK3 Action Spring, Carbine is a durable and long-lasting component. It shows no signs of wear and tear after several range sessions and hundreds of rounds fired.
Maintenance is minimal. I simply wipe it down with a lightly oiled cloth during routine rifle cleaning. The high-quality steel construction should resist corrosion and maintain its spring rate for a long time.
Accessories and Customization Options
The CMMG, Inc MK3 Action Spring, Carbine is a standalone component and does not require any additional accessories. However, it can be paired with other upgrades, such as heavier buffers or adjustable gas blocks, to further optimize cycling performance.
The spring is compatible with any AR-10 or CMMG Mk3 platform that uses a carbine-length buffer tube. It should also work with most aftermarket buffers and buffer tubes designed for these platforms.
Pros and Cons of CMMG, Inc MK3 Action Spring, Carbine
Pros
- Improved Cycling Reliability: Significantly reduces the chance of failures to eject or feed.
- Consistent Performance: Provides more consistent ejection patterns and bolt velocity.
- Easy Installation: Simple drop-in replacement with no special tools required.
- Durable Construction: Made of high-quality steel for long-lasting performance.
- Affordable Upgrade: A cost-effective way to improve the reliability of an AR-10 or CMMG Mk3 rifle.
Cons
- Potentially Too Stiff: May be too aggressive for some builds, especially those that are already over-gassed.
- Not Universally Compatible: Specifically designed for AR-10 and CMMG Mk3 platforms with carbine-length buffer tubes.
Who Should Buy CMMG, Inc MK3 Action Spring, Carbine?
The CMMG, Inc MK3 Action Spring, Carbine is perfect for AR-10 and CMMG Mk3 owners experiencing cycling issues, particularly failures to eject or inconsistent ejection patterns. It’s also a great upgrade for those looking to improve the overall reliability of their rifle.
Those who should skip this product are individuals with rifles that already cycle reliably or those with extremely lightweight builds that may not benefit from a stiffer spring. Anyone building a new AR-10 or CMMG Mk3 pistol/rifle could benefit from this spring for more efficient cycling.
A must-have accessory to pair with this product is an adjustable gas block. This allows you to fine-tune the gas pressure to optimize cycling performance, especially if the CMMG spring increases the bolt velocity too much.
Conclusion on CMMG, Inc MK3 Action Spring, Carbine
The CMMG, Inc MK3 Action Spring, Carbine is a simple but effective upgrade that can significantly improve the reliability and consistency of an AR-10 or CMMG Mk3 rifle. Its increased spring rate provides the force necessary to cycle rounds reliably, even with a wide range of ammunition types.
At a price of $5.89, the CMMG spring offers excellent value. It’s a small investment that can save you a lot of frustration at the range. For the price, it is easily worth the benefit.
I would definitely recommend the CMMG, Inc MK3 Action Spring, Carbine to anyone looking to improve the reliability of their AR-10 or CMMG Mk3 rifle. It’s a simple, affordable, and effective upgrade that can make a big difference. Don’t let cycling issues ruin your range day – upgrade your action spring and experience the difference!